This project is comprised of studies relating to the characterization of bacterial lipopolysaccharides (LPSs) by sodium dodecyl sulfate-polyacrylamide gel system. LPSs exhibit marked heterogeneity in silver-stained polyacrylamide gels. Using biochemically defined LPS chemotypes of Salmonella sp., we have shown that the morphological heterogeneity of LPS gel profiles correlates positively with biochemical variation in LPS composition. Development of several techniques including a silver stain which preferentially stains LPS in bacterial whole cell lysates, proteinase K digestion of whole cell lysates, and two-dimensional electrophoresis of LPS in polyacrylamide gels has enabled us to utilize SDS-PAGE as an effective tool for fingerprinting bacterial LPSs.